diff --git a/.github/workflows/rspec.yml b/.github/workflows/rspec.yml
index d2b4d7e..40f4a67 100644
--- a/.github/workflows/rspec.yml
+++ b/.github/workflows/rspec.yml
@@ -13,8 +13,8 @@ jobs:
       fail-fast: false
       matrix:
           ruby:
-              - 2.7
-              - 3.0
+              - '2.7'
+              - '3.0'
 
     steps:
     - name: Checkout repository